Abstract

We have measured the diffraction of metastable helium atoms by a transmission grating with a period of 500 nm. The atomic beam is derived from a supersonic nozzle by adiabatic gas expansion with a velocity ratio v/Δv 20; with the nozzle cooled to liquid nitrogen temperature, the corresponding de Broglie wave length of the helium atoms is 1.08 Å. We have observed diffraction peaks up to the third order with a good signal-to-noise ratio. The position and the height of the different orders are in satisfactory agreement with the measured grating shape and the mean velocity in the atomic beam. As was pointed out previously, such transmission gratings offer one way to realize an atom-wave interferometer.¹ In this context, our results demonstrate that an efficient diffraction can also be obtained with excited-state atoms: Here the use of metastable rare-gas atoms is of special interest because they are easy to handle and can be detected on almost zero background. As an alternative to the use of transmission gratings in matter-wave interferometry, we also discuss a simple double-slit arrangement that may provide another approach to the study of atomic interference phenomena.

© 1990 Optical Society of America